Footwear

ABSTRACT

A sandal having a sole and a band member integrally molded from synthetic resinous material having a foamy interior and a nonfoamy exterior. The specific gravity of the sole is lower than the specific gravity of the band member.

United States Patent Tatsuo Fukuoka N0. 3, 3-Ban, Z-chome Shin-minami-Fukushima, Tokushima, Japan 2,877

Jan. 14, 1970 May 4, 1971 inventor Appl. No. Filed Patented FOOTWEAR 4Claims, 6 Drawing Figs.

US. Cl

36/ 11.5 Int. Cl

Field ofSearch ..36/1l.5,25, 30, 32, 2.5

[56] References Cited UNITED STATES PATENTS 3,228,124 l/l966 Schwarz36/1 1.5 3,290,802 12/1966 Fukuoka 36/1 1.5 3,336,683 8/1967 Schellkopf36/1 1.5

Primary Examiner-Patrick D. Lawson Attorney-Dawson, Tilton, Fallon &Lungmus ABSTRACT: A sandal having a sole and a band member integrallymolded from synthetic resinous material having a foamy interior and anonfoamy exterior. The specific gravity of the sole is lower than thespecific gravity of the band member.

FOOTWEAR The present invention relates to an improvement of footwearsuch as sandal. slipper or the like integrally formed of syntheticresinous material.

A main object of the present invention is to provide a footwearcomprising a foamy interior portion adapted for providing resiliency anda nonfoamy outer layer integral therewith adapted for providingdurability and resistance against deformation of the footwear, andespecially the specific gravity of said foamy interior in a sole memberof the footwear being lower than that of a band member of the footwear.v

The further object of the present invention exists in providing thefootwear of which band member and sole member are integrally andinseparably molded from synthetic resinous material in a manner to beprovided with a foamy interior suitable resiliency and comfort, and anintegral nonfoamy outer layer suitable for durability and resistanceagainst deformation of the footwear, and especially foamy interior ofthe sole member of the footwear being lower, in specific gravitythereof, than foamy interior of the band member of the footwear.

Still further objects and advantages of the present invention willappear from the following disclosure of a preferred form of embodimentthereof taken in connection with the attached drawings, in which:

FIG. I is a perspective view of the sandal according to the presentinvention;

FIG. 2 is a longitudinal sectional view of the sandal take along theline II-II in FIG. 1;

FIG. 3 is a transversal sectional view of the sandal taken along theline III-III in FIG. 1;

FIG. 4 is a transversal sectional viewof the sandal along the line IV-IVin FIG. 1; I

FIG. 5 is a longitudinal sectional view of an apparatus available forproducing the sandal of the present invention; and

FIG. 6 is an enlarged transversal sectional paratus taken along thelineVI-VI in FIG. 5.

Referring to the drawings, illustrated therein is an improved sandalaccording to the present invention. Be molded from synthetic resinousmaterial said sandal of which composition will be hereinafter describedin detail.

The sandal comprises a band member 1 and a sole member 2 having a uniqueupper surface 2A and a heel 28, said band member and sole member beingsimultaneously and integrally molded in one operation and step by meansof a mold or apparatus which will be hereinafter described. I

Said sandal including the band member and sole member is, as shown inFIGS. 2 to 4, molded so as to form an integral unit of a uniquely formedsynthetic resinous material having a foamy interior 3 and a nonfoamyouter layer 4 surrounding said foamy interior.

As a consequence of said unique structure, the foamy interior portion ofthe resinous material provides a highly resilient and pliable cushionyeffect, thereby effecting the comfort in use, while the nonfoamy(relatively firm) outer layer resists against deformation of the andalcaused by the users own weight. In addition, said nonfoamy outer layerbeing integral over the band member and sole member facilitates the firmand integral connection of the sole member and bank member, further isprovided with a water insulation ability for preventing watersaturation. And as a result of the existence of the bubblelike foamyportion in the foamy layer, there may be contained air in said foamylayer, thereby reducing the weight of the sandal. And especially, it ishereby pointed out as the specific feature of the present invention thatspecific gravity of the sole member is different from that of the bandmember, that is, the former is lower than the latter by approximately0.2 to 0.4 (specific gravity).

The followingtables show examples of the specific gravities of thesandals produced according to the present invention, in which table Ashows examples of having used vinyl chloride as the material thereof andtable B shows those of having used ethylenevinyl acetate copolymer asthe material thereof:

taken view of the ap- TABLE A No. 1 No. 2 No. 3 No. 4

Specific gravity of the sandal 0.697 0. 609 0. 655 0. 655 Specificgravity of the band memben... 0. 919 0.912 0. 920 0. 954 Specificgravity of the sole men1ber 0.651 0. 542 0. 616 0.606 Difference betweengravities of band member and sole member 0. 268 0.370 0.303 0. 348

TABLE B No. 5 No. 6 No. 7 No. 8

Specific gravity of the sandal 0.518 0.572 0.474 0.602 Specific gravityof the band member 0.793 0.778 0. 714 0. 750 Specific gravity of thesole member 0. 444 0.515 0. 432 0. 443 Difierence between gravities ofband member and sole member 0. 349

Since the specific gravity of the sole member to occupy 80 percent ofthe whole weight of the sandal is lower than that of the band member,whatever the gravity of the band member may be in its specific gravityhigher, for example, being 0.954 as shown in the example No. 4 in tableA, the whole specific gravity of the sandal will never be more than0.655, whereby the sandal or footwear produced according to the presentinvention facilitates reduction of its whole weight and also the bandmember being liable to be damaged can be reinforced by higher specificgravity thereof.

According to the present invention, the upper surface 2A of the solemember is provided with a curved shape in conformity with figure of theuser's sole in order to provide the user with the comfort to wear.

In FIGS, 1 to 4, a portion 5 of the surface 2A corresponding to theplantar of the users sole and an edge 6 of said upper surface 2A aregently elevated and another portions of the upper surface being formedby gently sloped concaves 7 and 8. The aforesaid elevatedportions andconcaves are integrally connected to each other through the gentlycurved face.

By the above-described construction users sole can be brought intoperfect snug-fit contact with the upper surface of the sole member andaccordingly the wearer can easily walk without slippage and fatigue,with extremely improved wearing comfort.

FIGS. 5 and 6 show an embodiment of an apparatus available for producingthe sandal according to the present invention. The apparatus isassembled with a number of mold pieces 10 and provided with a moldingchamber 11 formed in a profile in conformity with outer figure of thesandal to be manufactured. A movable mold piece 10A comprising a lowersurface of a space 11A adapted for producing said sole is connected toplungers l2 constructed to be driven upwardly and downwardly bymeans ofsuitable power source (not shown).

Through an inlet 13 a molten synthetic resinous material to be afterdescribed is discharged into the molding chamber 11 and secondly themovable mold piece 10A is downwardly moved for the predetermined measureby plunger so as to expand the capacity of the space 11A. As a result ofit, the specific gravity of the sole member will be lowered by expandingcapacity of the space 11A. In such a case, the molten synthetic resinmaterial existing within a space 118 adapted for producing the bandmember will be rapidly cooled and hardened rather than the moltenmaterial existing within the space 11A by surrounding mold piece becauseof small clearance of the space 118, thereby preventing the inflow ofthe material into the expanded space 11A and obtaining theaforementioned different specific gravities of band member and solemember of the sandal.

It will be understood that the desired specific gravities of band memberand sole member such as shown in examples of tables A and B are easilyobtained by the step for adjusting momentum of the mold piece 10A.

methacrylate and vinylidene chloride;

As hereinabove mentioned, the method of manufacturingthe synthetic resinmaterial featured in the present invention is not ony of criticalimportance, but is a highly complex and specialized process, as will nowbe described.

A number of various thermoplastic resinous materials which can beexpanded or formed may be used-to form the novel foamed materialutilized in the present invention. However, and without intending to berestricted thereto, the invention is particularly adapted to be formedof granules or beads of polystyrene. Said polystyrene particles may bein an essentially linear or in a cross-linked form, as being generallyrepresentative of expandable thermoplastic resinous materials and asbeing especially representative of alkenyl aromatic compounds whichcontain at least one alkenyl aromatic compound having the generalformula Ar CR =Cl-l wherein Ar is an aromatic compound and R is selectedfrom the group consisting of a hydrogen atom and a methyl radical.Expandable thermoplastic copolymers of styrene and polymers andcopolymers of a-methyl styrene, ar-methyl styrene or vinyltoluene,monoand di-chlorostyrene, including copolymers containing small amountsof such materials as divinylbenzene may frequently be utilized withbenefits commensurate with those which are derivable from employment ofpolystyrene. Often this may also be the case with other expandablethermoplastic resinous materials including various copolymers ofvinylidene chloride which are frequently generically described as beingsarans and thermoplastic resinous materials which may be comprised ofpolymers and copolymers of methyl methacrylate, ethyl acrylate and otherderivatives of acrylic acid such as their homopolymers and copolymers ofmethyl polymers and copolymers of vinyl acetate and vinyl butyral andthe like; and various thermoplastic or thermoplastified derivatives ofcellulose including cellulose nitrate and cellulose acetate. Crosslinkedmaterials usually have greater thermal stability and frequently tend toproduce stronger, less heat-sensitive foam structures.

The blowing agents employed for the expandable thermoplastic resinousmaterial may be those which are com monly utilized includingdichlorodifluoromethane, carbon dioxide, pentane and other low-boilinghydrocarbons or other suitable materials such as heat sensitivegas-generating agents and the like. Conventional amounts of the blowingagent may be incorporated in the discrete particles of thermoplasticresinous material to render it suitably expandable. Thus, an in-' Toform the foamed material, the preferred mefiiod comprises charging amass of said granules into the dischargeable injection chamber-of aninjection-molding apparatus; then, in intermittent molding cycles,forcing said mass under pressure sequentially in and through a firstcold zone in said chamber wherein a portion of said mass is compacted insolid granular form while being maintained at a temperature beneath itsfoaming temperature; a second heated zone adjacent to the first zone insaid chamber wherein a portion of said mass is heated to a flowablecondition under the application of an adequate quantity of heat to causeit to attain a foaming temperature; the solid compacted portion of themass in the first zone continuously maintaining the heated portion ofsaid mass in the second zone to restrain substantial foaming thereinthroughout said intermittent cycles; and a discharge zone in saidchamber from which a portion of said heated mass is injected to fill aretractable mold form having an enlargeable cavity wherein the injectedmass is initially exteriorly cooled against the' mold form to form asolidified surface layer while being maintained under pressure; andfinally relieving the pressure and enlarging the mold form to permit thecentral, relatively uncooled heated mass to expand and force thesolidified surface layer against the enlarged confining limits of themold form to orm said sandwich construction molded foam structure.

While the present invention has been illustrated and described hereinwith respect to a preferred embodiment, it is not desired to limit theinvention only to the embodiment, but the invention should be consideredto include all the sub stitutes, modifications and equivalents which areencompassed within the essential part of the invention to be set forthin the scope of the underwritten claims and within the scope of thespirit exhibited in the intention of the inventor.

lclaim:

1. A footwear comprising a band member and a sole member both of whichare integrally and inseparably molded from synthetic resinous-materialhaving foamy interior, said sole member of which specific gravity beinglower than that of the band member with the difference approximately 0.2to 0.4.

2. A footwear as claimed in claim 1, wherein said specific gravity ofthe band member is approximately 0.70 to 0.96 while that of the solemember being approximately 0.40 to 0.66.

3. A footwear as claimed in claim 1, wherein said foamy interior isprovided with a relatively firm and nonfoamy outer layer integraltherewith around thereof.

4. A footwear as claimed in claims 1, 2 or 3, wherein said sole memberis provided with a unique upper surface formed with a shape inconformity with profile of the users sole.

1. A footwear comprising a band member and a sole member both of whichare integrally and inseparably molded from synthetic resinous materialhaving foamy interior, said sole member of which specific gravity beinglower than that of the band member with the difference approximately 0.2to 0.4.
 2. A footwear as claimed in claim 1, wherein said specificgravity of the band member is approximately 0.70 to 0.96 while that ofthe sole member being approximately 0.40 to 0.66.
 3. A footwear asclaimed in claim 1, wherein said foamy interior is provided with arelatively firm and nonfoamy outer layer integral therewith aroundthereof.
 4. A footwear as claimed in claims 1, 2 or 3, wherein said solemember is provided with a unique upper surface formed with a shape inconformity with profile of the user''s sole.